Nanogram-scale boron isotope analysis through micro-distillation and Nu Plasma 3 MC-ICP-MS.

The determination of boron isotopes (δ11B) represents a powerful tool for a variety of applications such as the reconstruction of past ocean pH and atmospheric pCO2 from the analysis of marine biogenic carbonates. In recent years, MC-ICP-MS has gained popularity over other techniques thanks to its superior sample throughput and high ionization efficiency. This study evaluates, for the first time, the performance of the Nu Instruments Plasma 3 MC-ICP-MS for measuring δ11B using different sample introduction systems and detector configurations. The main goal is to provide a detailed methodology for nanogram-scale boron isotope analysis through a straightforward approach that can be easily adopted. Boron (B) purification from the carbonate matrix was performed through micro-distillation, using a temperature of 95 °C and a minimum heating duration of 15 h, allowing the full recovery of B from up to 3 mg of carbonate mass. We attained blank values (on average 14 ± 6 pg, 1 SD, n = 27) comparable to the lowest micro-distillation blanks reported in the literature. Three sample introduction systems were tested, and the 30 µL min-1 nebuliser system outperformed the 50 and 170 µL min-1 systems in terms of signal intensity per mass of B. Two detector configurations were used based on the total boron signal intensity achieved: (1) FC11/FC12, with two Faraday cups fitted to 1011 Ω and 1012 Ω amplifier resistors to detect 11B and 10B ion beams, respectively, and (2) FC12/IC, with which we investigated, for the first time, the feasibility of combining an ion counter for detecting 10B, and a Faraday cup fitted to a 1012 Ω amplifier for 11B. The FC12/IC configuration provided accurate results compared to the use of two Faraday cups for total boron signals lower than 0.35 V (∼12 ng of B in the analysed solution). The proposed analytical procedure was validated through the analysis of several reference materials with varying boron amounts, including clam JCt-1, coral JCp-1, NIST RM 8301 Foram and Coral solutions, and boric acid ERM-AE121. Furthermore, the long-term reproducibility was assessed with two in-house standards (coral CLD-1 and foraminifera GINF-1), providing values of 25.68 ± 0.23 ‰ (2SD, n = 53; with 14-36 ng of B) and 14.90 ± 0.16 ‰ (2SD, n = 12; with 11-16 ng of B), respectively.

Using near-infrared spectroscopy myocardial oximetry to monitor myocardial oxygen balance in a swine model of cardiac surgery: a descriptive study.

Monitoring of the adequacy of myocardial protection with cardioplegia is nearly non-existent in clinical cardiac surgical practice and instead relies on well-defined protocols for delivery of cardioplegia often resulting in inadequate protection. We hypothesized that Near Infrared Spectroscopy technology could be useful in the monitoring of the myocardial oxygen state by attaching the monitors to the epicardium in a porcine model of cardiac surgery. The experiments were conducted with 3 different protocols of 2 pigs each for a total of 6 pigs. The objective was to induce episodic, oxygen supply-demand mismatch. Methods for decreased supply included decreasing coronary blood flow, coronary blood hypoxemia, coronary occlusion, hypovolemia, and hypotension. Methods for increase demand included rapid ventricular pacing and the administration of isoproterenol. Changes in myocardial tissue oximetry were measured and this measurement was then correlated with blood hemoglobin saturations of oxygen from coronary sinus blood samples. We found that decreases in myocardial oxygen supply or increases in demand due to any of the various experimental conditions led to decreases in both myocardial tissue oximetry and hemoglobin oxygen saturation of coronary sinus blood with recovery when the conditions were returned to baseline. Correlation between myocardial tissue oximetry and hemoglobin oxygen saturation of coronary sinus blood was moderate to strong under all tested conditions. This may have translational applications as a monitor of adequacy of myocardial protection and the detection of coronary occlusion.

Use of real-time three-dimensional transesophageal echocardiography in type A aortic dissections: advantages of 3D TEE illustrated in three cases.

Stanford type A aortic dissections often present to the hospital requiring emergent surgical intervention. Initial diagnosis is usually made by computed tomography; however transesophageal echocardiography (TEE) can further characterize aortic dissections with specific advantages: It may be performed on an unstable patient, it can be used intra-operatively, and it has the ability to provide continuous real-time information. Three-dimensional (3D) TEE has become more accessible over recent years allowing it to serve as an additional tool in the operating room. We present a case series of three patients presenting with type A aortic dissections and the advantages of intra-operative 3D TEE to diagnose the extent of dissection in each case. Prior case reports have demonstrated the use of 3D TEE in type A aortic dissections to characterize the extent of dissection and involvement of neighboring structures. In our three cases described, 3D TEE provided additional understanding of spatial relationships between the dissection flap and neighboring structures such as the aortic valve and coronary orifices that were not fully appreciated with two-dimensional TEE, which affected surgical decisions in the operating room. This case series demonstrates the utility and benefit of real-time 3D TEE during intra-operative management of a type A aortic dissection.

Multimodal neuromonitoring in pediatric cardiac anesthesia.

Despite significant improvements in overall outcome, neurological injury remains a feared complication following pediatric congenital heart surgery (CHS). Only if adverse events are detected early enough, can effective actions be initiated preventing potentially serious injury. The multifactorial etiology of neurological injury in CHS patients makes it unlikely that one single monitoring modality will be effective in capturing all possible threats. Improving current and developing new technologies and combining them according to the concept of multimodal monitoring may allow for early detection and possible intervention with the goal to further improve neurological outcome in children undergoing CHS.

Rapid ventricular pacing: a novel technique to decrease cardiac output for giant basilar aneurysm surgery.

A case of a 49 year old man with a giant basilar artery aneurysm requiring rapid ventricular pacing is presented. Rapid ventricular pacing decreased aneurysm size and increased operative exposure, which aided surgical decision making. It also provided decreased wall tension in the aneurysm.

A case of severe SAM following a David procedure.

We report a case of hemodynamically significant systolic anterior motion of the mitral valve following a David procedure. Although systolic anterior motion of the mitral valve has been reported following mitral valve repair or replacement and aortic valve replacement, it has not been previously described following isolated ascending aortic surgery.

Thoracic paravertebral block for implantable cardioverter-defibrillator and laser lead extraction.

Implantable cardioverter defibrillators (ICDs) are routinely placed in the cardiac electrophysiology laboratory. Previously, these procedures were performed in the operating room during general anesthesia. In recent years, electrophysiologists have been performing these procedures using local anesthetics in conjunction with intravenous sedation. We report a case in which thoracic paravertebral blocks with mild sedation were successful for infected ICD and laser lead extraction. Randomized, controlled trials are required to determine whether thoracic paravertebral block with sedation is more effective than local anesthesia with sedation in providing adequate anesthesia for ICD placement and extraction.